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  <div class="section" id="module-pkgutil">
<span id="pkgutil-package-extension-utility"></span><h1><a class="reference internal" href="#module-pkgutil" title="pkgutil: Utilities for the import system."><code class="xref py py-mod docutils literal notranslate"><span class="pre">pkgutil</span></code></a> — Package extension utility<a class="headerlink" href="#module-pkgutil" title="Permalink to this headline">¶</a></h1>
<p><strong>Source code:</strong> <a class="reference external" href="https://github.com/python/cpython/tree/3.8/Lib/pkgutil.py">Lib/pkgutil.py</a></p>
<hr class="docutils" />
<p>This module provides utilities for the import system, in particular package
support.</p>
<dl class="class">
<dt id="pkgutil.ModuleInfo">
<em class="property">class </em><code class="sig-prename descclassname">pkgutil.</code><code class="sig-name descname">ModuleInfo</code><span class="sig-paren">(</span><em class="sig-param">module_finder</em>, <em class="sig-param">name</em>, <em class="sig-param">ispkg</em><span class="sig-paren">)</span><a class="headerlink" href="#pkgutil.ModuleInfo" title="Permalink to this definition">¶</a></dt>
<dd><p>A namedtuple that holds a brief summary of a module’s info.</p>
<div class="versionadded">
<p><span class="versionmodified added">New in version 3.6.</span></p>
</div>
</dd></dl>

<dl class="function">
<dt id="pkgutil.extend_path">
<code class="sig-prename descclassname">pkgutil.</code><code class="sig-name descname">extend_path</code><span class="sig-paren">(</span><em class="sig-param">path</em>, <em class="sig-param">name</em><span class="sig-paren">)</span><a class="headerlink" href="#pkgutil.extend_path" title="Permalink to this definition">¶</a></dt>
<dd><p>Extend the search path for the modules which comprise a package.  Intended
use is to place the following code in a package’s <code class="file docutils literal notranslate"><span class="pre">__init__.py</span></code>:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="kn">from</span> <span class="nn">pkgutil</span> <span class="kn">import</span> <span class="n">extend_path</span>
<span class="n">__path__</span> <span class="o">=</span> <span class="n">extend_path</span><span class="p">(</span><span class="n">__path__</span><span class="p">,</span> <span class="vm">__name__</span><span class="p">)</span>
</pre></div>
</div>
<p>This will add to the package’s <code class="docutils literal notranslate"><span class="pre">__path__</span></code> all subdirectories of directories
on <code class="docutils literal notranslate"><span class="pre">sys.path</span></code> named after the package.  This is useful if one wants to
distribute different parts of a single logical package as multiple
directories.</p>
<p>It also looks for <code class="file docutils literal notranslate"><span class="pre">*.pkg</span></code> files beginning where <code class="docutils literal notranslate"><span class="pre">*</span></code> matches the
<em>name</em> argument.  This feature is similar to <code class="file docutils literal notranslate"><span class="pre">*.pth</span></code> files (see the
<a class="reference internal" href="site.html#module-site" title="site: Module responsible for site-specific configuration."><code class="xref py py-mod docutils literal notranslate"><span class="pre">site</span></code></a> module for more information), except that it doesn’t special-case
lines starting with <code class="docutils literal notranslate"><span class="pre">import</span></code>.  A <code class="file docutils literal notranslate"><span class="pre">*.pkg</span></code> file is trusted at face
value: apart from checking for duplicates, all entries found in a
<code class="file docutils literal notranslate"><span class="pre">*.pkg</span></code> file are added to the path, regardless of whether they exist
on the filesystem.  (This is a feature.)</p>
<p>If the input path is not a list (as is the case for frozen packages) it is
returned unchanged.  The input path is not modified; an extended copy is
returned.  Items are only appended to the copy at the end.</p>
<p>It is assumed that <a class="reference internal" href="sys.html#sys.path" title="sys.path"><code class="xref py py-data docutils literal notranslate"><span class="pre">sys.path</span></code></a> is a sequence.  Items of <a class="reference internal" href="sys.html#sys.path" title="sys.path"><code class="xref py py-data docutils literal notranslate"><span class="pre">sys.path</span></code></a>
that are not strings referring to existing directories are ignored. Unicode
items on <a class="reference internal" href="sys.html#sys.path" title="sys.path"><code class="xref py py-data docutils literal notranslate"><span class="pre">sys.path</span></code></a> that cause errors when used as filenames may cause
this function to raise an exception (in line with <a class="reference internal" href="os.path.html#os.path.isdir" title="os.path.isdir"><code class="xref py py-func docutils literal notranslate"><span class="pre">os.path.isdir()</span></code></a>
behavior).</p>
</dd></dl>

<dl class="class">
<dt id="pkgutil.ImpImporter">
<em class="property">class </em><code class="sig-prename descclassname">pkgutil.</code><code class="sig-name descname">ImpImporter</code><span class="sig-paren">(</span><em class="sig-param">dirname=None</em><span class="sig-paren">)</span><a class="headerlink" href="#pkgutil.ImpImporter" title="Permalink to this definition">¶</a></dt>
<dd><p><span class="target" id="index-0"></span><a class="pep reference external" href="https://www.python.org/dev/peps/pep-0302"><strong>PEP 302</strong></a> Finder that wraps Python’s “classic” import algorithm.</p>
<p>If <em>dirname</em> is a string, a <span class="target" id="index-1"></span><a class="pep reference external" href="https://www.python.org/dev/peps/pep-0302"><strong>PEP 302</strong></a> finder is created that searches that
directory.  If <em>dirname</em> is <code class="docutils literal notranslate"><span class="pre">None</span></code>, a <span class="target" id="index-2"></span><a class="pep reference external" href="https://www.python.org/dev/peps/pep-0302"><strong>PEP 302</strong></a> finder is created that
searches the current <a class="reference internal" href="sys.html#sys.path" title="sys.path"><code class="xref py py-data docutils literal notranslate"><span class="pre">sys.path</span></code></a>, plus any modules that are frozen or
built-in.</p>
<p>Note that <a class="reference internal" href="#pkgutil.ImpImporter" title="pkgutil.ImpImporter"><code class="xref py py-class docutils literal notranslate"><span class="pre">ImpImporter</span></code></a> does not currently support being used by
placement on <a class="reference internal" href="sys.html#sys.meta_path" title="sys.meta_path"><code class="xref py py-data docutils literal notranslate"><span class="pre">sys.meta_path</span></code></a>.</p>
<div class="deprecated">
<p><span class="versionmodified deprecated">Deprecated since version 3.3: </span>This emulation is no longer needed, as the standard import mechanism
is now fully <span class="target" id="index-3"></span><a class="pep reference external" href="https://www.python.org/dev/peps/pep-0302"><strong>PEP 302</strong></a> compliant and available in <a class="reference internal" href="importlib.html#module-importlib" title="importlib: The implementation of the import machinery."><code class="xref py py-mod docutils literal notranslate"><span class="pre">importlib</span></code></a>.</p>
</div>
</dd></dl>

<dl class="class">
<dt id="pkgutil.ImpLoader">
<em class="property">class </em><code class="sig-prename descclassname">pkgutil.</code><code class="sig-name descname">ImpLoader</code><span class="sig-paren">(</span><em class="sig-param">fullname</em>, <em class="sig-param">file</em>, <em class="sig-param">filename</em>, <em class="sig-param">etc</em><span class="sig-paren">)</span><a class="headerlink" href="#pkgutil.ImpLoader" title="Permalink to this definition">¶</a></dt>
<dd><p><a class="reference internal" href="../glossary.html#term-loader"><span class="xref std std-term">Loader</span></a> that wraps Python’s “classic” import algorithm.</p>
<div class="deprecated">
<p><span class="versionmodified deprecated">Deprecated since version 3.3: </span>This emulation is no longer needed, as the standard import mechanism
is now fully <span class="target" id="index-4"></span><a class="pep reference external" href="https://www.python.org/dev/peps/pep-0302"><strong>PEP 302</strong></a> compliant and available in <a class="reference internal" href="importlib.html#module-importlib" title="importlib: The implementation of the import machinery."><code class="xref py py-mod docutils literal notranslate"><span class="pre">importlib</span></code></a>.</p>
</div>
</dd></dl>

<dl class="function">
<dt id="pkgutil.find_loader">
<code class="sig-prename descclassname">pkgutil.</code><code class="sig-name descname">find_loader</code><span class="sig-paren">(</span><em class="sig-param">fullname</em><span class="sig-paren">)</span><a class="headerlink" href="#pkgutil.find_loader" title="Permalink to this definition">¶</a></dt>
<dd><p>Retrieve a module <a class="reference internal" href="../glossary.html#term-loader"><span class="xref std std-term">loader</span></a> for the given <em>fullname</em>.</p>
<p>This is a backwards compatibility wrapper around
<a class="reference internal" href="importlib.html#importlib.util.find_spec" title="importlib.util.find_spec"><code class="xref py py-func docutils literal notranslate"><span class="pre">importlib.util.find_spec()</span></code></a> that converts most failures to
<a class="reference internal" href="exceptions.html#ImportError" title="ImportError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">ImportError</span></code></a> and only returns the loader rather than the full
<code class="xref py py-class docutils literal notranslate"><span class="pre">ModuleSpec</span></code>.</p>
<div class="versionchanged">
<p><span class="versionmodified changed">Changed in version 3.3: </span>Updated to be based directly on <a class="reference internal" href="importlib.html#module-importlib" title="importlib: The implementation of the import machinery."><code class="xref py py-mod docutils literal notranslate"><span class="pre">importlib</span></code></a> rather than relying
on the package internal <span class="target" id="index-5"></span><a class="pep reference external" href="https://www.python.org/dev/peps/pep-0302"><strong>PEP 302</strong></a> import emulation.</p>
</div>
<div class="versionchanged">
<p><span class="versionmodified changed">Changed in version 3.4: </span>Updated to be based on <span class="target" id="index-6"></span><a class="pep reference external" href="https://www.python.org/dev/peps/pep-0451"><strong>PEP 451</strong></a></p>
</div>
</dd></dl>

<dl class="function">
<dt id="pkgutil.get_importer">
<code class="sig-prename descclassname">pkgutil.</code><code class="sig-name descname">get_importer</code><span class="sig-paren">(</span><em class="sig-param">path_item</em><span class="sig-paren">)</span><a class="headerlink" href="#pkgutil.get_importer" title="Permalink to this definition">¶</a></dt>
<dd><p>Retrieve a <a class="reference internal" href="../glossary.html#term-finder"><span class="xref std std-term">finder</span></a> for the given <em>path_item</em>.</p>
<p>The returned finder is cached in <a class="reference internal" href="sys.html#sys.path_importer_cache" title="sys.path_importer_cache"><code class="xref py py-data docutils literal notranslate"><span class="pre">sys.path_importer_cache</span></code></a> if it was
newly created by a path hook.</p>
<p>The cache (or part of it) can be cleared manually if a rescan of
<a class="reference internal" href="sys.html#sys.path_hooks" title="sys.path_hooks"><code class="xref py py-data docutils literal notranslate"><span class="pre">sys.path_hooks</span></code></a> is necessary.</p>
<div class="versionchanged">
<p><span class="versionmodified changed">Changed in version 3.3: </span>Updated to be based directly on <a class="reference internal" href="importlib.html#module-importlib" title="importlib: The implementation of the import machinery."><code class="xref py py-mod docutils literal notranslate"><span class="pre">importlib</span></code></a> rather than relying
on the package internal <span class="target" id="index-7"></span><a class="pep reference external" href="https://www.python.org/dev/peps/pep-0302"><strong>PEP 302</strong></a> import emulation.</p>
</div>
</dd></dl>

<dl class="function">
<dt id="pkgutil.get_loader">
<code class="sig-prename descclassname">pkgutil.</code><code class="sig-name descname">get_loader</code><span class="sig-paren">(</span><em class="sig-param">module_or_name</em><span class="sig-paren">)</span><a class="headerlink" href="#pkgutil.get_loader" title="Permalink to this definition">¶</a></dt>
<dd><p>Get a <a class="reference internal" href="../glossary.html#term-loader"><span class="xref std std-term">loader</span></a> object for <em>module_or_name</em>.</p>
<p>If the module or package is accessible via the normal import mechanism, a
wrapper around the relevant part of that machinery is returned.  Returns
<code class="docutils literal notranslate"><span class="pre">None</span></code> if the module cannot be found or imported.  If the named module is
not already imported, its containing package (if any) is imported, in order
to establish the package <code class="docutils literal notranslate"><span class="pre">__path__</span></code>.</p>
<div class="versionchanged">
<p><span class="versionmodified changed">Changed in version 3.3: </span>Updated to be based directly on <a class="reference internal" href="importlib.html#module-importlib" title="importlib: The implementation of the import machinery."><code class="xref py py-mod docutils literal notranslate"><span class="pre">importlib</span></code></a> rather than relying
on the package internal <span class="target" id="index-8"></span><a class="pep reference external" href="https://www.python.org/dev/peps/pep-0302"><strong>PEP 302</strong></a> import emulation.</p>
</div>
<div class="versionchanged">
<p><span class="versionmodified changed">Changed in version 3.4: </span>Updated to be based on <span class="target" id="index-9"></span><a class="pep reference external" href="https://www.python.org/dev/peps/pep-0451"><strong>PEP 451</strong></a></p>
</div>
</dd></dl>

<dl class="function">
<dt id="pkgutil.iter_importers">
<code class="sig-prename descclassname">pkgutil.</code><code class="sig-name descname">iter_importers</code><span class="sig-paren">(</span><em class="sig-param">fullname=''</em><span class="sig-paren">)</span><a class="headerlink" href="#pkgutil.iter_importers" title="Permalink to this definition">¶</a></dt>
<dd><p>Yield <a class="reference internal" href="../glossary.html#term-finder"><span class="xref std std-term">finder</span></a> objects for the given module name.</p>
<p>If fullname contains a ‘.’, the finders will be for the package
containing fullname, otherwise they will be all registered top level
finders (i.e. those on both sys.meta_path and sys.path_hooks).</p>
<p>If the named module is in a package, that package is imported as a side
effect of invoking this function.</p>
<p>If no module name is specified, all top level finders are produced.</p>
<div class="versionchanged">
<p><span class="versionmodified changed">Changed in version 3.3: </span>Updated to be based directly on <a class="reference internal" href="importlib.html#module-importlib" title="importlib: The implementation of the import machinery."><code class="xref py py-mod docutils literal notranslate"><span class="pre">importlib</span></code></a> rather than relying
on the package internal <span class="target" id="index-10"></span><a class="pep reference external" href="https://www.python.org/dev/peps/pep-0302"><strong>PEP 302</strong></a> import emulation.</p>
</div>
</dd></dl>

<dl class="function">
<dt id="pkgutil.iter_modules">
<code class="sig-prename descclassname">pkgutil.</code><code class="sig-name descname">iter_modules</code><span class="sig-paren">(</span><em class="sig-param">path=None</em>, <em class="sig-param">prefix=''</em><span class="sig-paren">)</span><a class="headerlink" href="#pkgutil.iter_modules" title="Permalink to this definition">¶</a></dt>
<dd><p>Yields <a class="reference internal" href="#pkgutil.ModuleInfo" title="pkgutil.ModuleInfo"><code class="xref py py-class docutils literal notranslate"><span class="pre">ModuleInfo</span></code></a> for all submodules on <em>path</em>, or, if
<em>path</em> is <code class="docutils literal notranslate"><span class="pre">None</span></code>, all top-level modules on <code class="docutils literal notranslate"><span class="pre">sys.path</span></code>.</p>
<p><em>path</em> should be either <code class="docutils literal notranslate"><span class="pre">None</span></code> or a list of paths to look for modules in.</p>
<p><em>prefix</em> is a string to output on the front of every module name on output.</p>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p>Only works for a <a class="reference internal" href="../glossary.html#term-finder"><span class="xref std std-term">finder</span></a> which defines an <code class="docutils literal notranslate"><span class="pre">iter_modules()</span></code>
method. This interface is non-standard, so the module also provides
implementations for <a class="reference internal" href="importlib.html#importlib.machinery.FileFinder" title="importlib.machinery.FileFinder"><code class="xref py py-class docutils literal notranslate"><span class="pre">importlib.machinery.FileFinder</span></code></a> and
<a class="reference internal" href="zipimport.html#zipimport.zipimporter" title="zipimport.zipimporter"><code class="xref py py-class docutils literal notranslate"><span class="pre">zipimport.zipimporter</span></code></a>.</p>
</div>
<div class="versionchanged">
<p><span class="versionmodified changed">Changed in version 3.3: </span>Updated to be based directly on <a class="reference internal" href="importlib.html#module-importlib" title="importlib: The implementation of the import machinery."><code class="xref py py-mod docutils literal notranslate"><span class="pre">importlib</span></code></a> rather than relying
on the package internal <span class="target" id="index-11"></span><a class="pep reference external" href="https://www.python.org/dev/peps/pep-0302"><strong>PEP 302</strong></a> import emulation.</p>
</div>
</dd></dl>

<dl class="function">
<dt id="pkgutil.walk_packages">
<code class="sig-prename descclassname">pkgutil.</code><code class="sig-name descname">walk_packages</code><span class="sig-paren">(</span><em class="sig-param">path=None</em>, <em class="sig-param">prefix=''</em>, <em class="sig-param">onerror=None</em><span class="sig-paren">)</span><a class="headerlink" href="#pkgutil.walk_packages" title="Permalink to this definition">¶</a></dt>
<dd><p>Yields <a class="reference internal" href="#pkgutil.ModuleInfo" title="pkgutil.ModuleInfo"><code class="xref py py-class docutils literal notranslate"><span class="pre">ModuleInfo</span></code></a> for all modules recursively on
<em>path</em>, or, if <em>path</em> is <code class="docutils literal notranslate"><span class="pre">None</span></code>, all accessible modules.</p>
<p><em>path</em> should be either <code class="docutils literal notranslate"><span class="pre">None</span></code> or a list of paths to look for modules in.</p>
<p><em>prefix</em> is a string to output on the front of every module name on output.</p>
<p>Note that this function must import all <em>packages</em> (<em>not</em> all modules!) on
the given <em>path</em>, in order to access the <code class="docutils literal notranslate"><span class="pre">__path__</span></code> attribute to find
submodules.</p>
<p><em>onerror</em> is a function which gets called with one argument (the name of the
package which was being imported) if any exception occurs while trying to
import a package.  If no <em>onerror</em> function is supplied, <a class="reference internal" href="exceptions.html#ImportError" title="ImportError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">ImportError</span></code></a>s
are caught and ignored, while all other exceptions are propagated,
terminating the search.</p>
<p>Examples:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="c1"># list all modules python can access</span>
<span class="n">walk_packages</span><span class="p">()</span>

<span class="c1"># list all submodules of ctypes</span>
<span class="n">walk_packages</span><span class="p">(</span><span class="n">ctypes</span><span class="o">.</span><span class="n">__path__</span><span class="p">,</span> <span class="n">ctypes</span><span class="o">.</span><span class="vm">__name__</span> <span class="o">+</span> <span class="s1">&#39;.&#39;</span><span class="p">)</span>
</pre></div>
</div>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p>Only works for a <a class="reference internal" href="../glossary.html#term-finder"><span class="xref std std-term">finder</span></a> which defines an <code class="docutils literal notranslate"><span class="pre">iter_modules()</span></code>
method. This interface is non-standard, so the module also provides
implementations for <a class="reference internal" href="importlib.html#importlib.machinery.FileFinder" title="importlib.machinery.FileFinder"><code class="xref py py-class docutils literal notranslate"><span class="pre">importlib.machinery.FileFinder</span></code></a> and
<a class="reference internal" href="zipimport.html#zipimport.zipimporter" title="zipimport.zipimporter"><code class="xref py py-class docutils literal notranslate"><span class="pre">zipimport.zipimporter</span></code></a>.</p>
</div>
<div class="versionchanged">
<p><span class="versionmodified changed">Changed in version 3.3: </span>Updated to be based directly on <a class="reference internal" href="importlib.html#module-importlib" title="importlib: The implementation of the import machinery."><code class="xref py py-mod docutils literal notranslate"><span class="pre">importlib</span></code></a> rather than relying
on the package internal <span class="target" id="index-12"></span><a class="pep reference external" href="https://www.python.org/dev/peps/pep-0302"><strong>PEP 302</strong></a> import emulation.</p>
</div>
</dd></dl>

<dl class="function">
<dt id="pkgutil.get_data">
<code class="sig-prename descclassname">pkgutil.</code><code class="sig-name descname">get_data</code><span class="sig-paren">(</span><em class="sig-param">package</em>, <em class="sig-param">resource</em><span class="sig-paren">)</span><a class="headerlink" href="#pkgutil.get_data" title="Permalink to this definition">¶</a></dt>
<dd><p>Get a resource from a package.</p>
<p>This is a wrapper for the <a class="reference internal" href="../glossary.html#term-loader"><span class="xref std std-term">loader</span></a>
<a class="reference internal" href="importlib.html#importlib.abc.ResourceLoader.get_data" title="importlib.abc.ResourceLoader.get_data"><code class="xref py py-meth docutils literal notranslate"><span class="pre">get_data</span></code></a> API.  The
<em>package</em> argument should be the name of a package, in standard module format
(<code class="docutils literal notranslate"><span class="pre">foo.bar</span></code>).  The <em>resource</em> argument should be in the form of a relative
filename, using <code class="docutils literal notranslate"><span class="pre">/</span></code> as the path separator.  The parent directory name
<code class="docutils literal notranslate"><span class="pre">..</span></code> is not allowed, and nor is a rooted name (starting with a <code class="docutils literal notranslate"><span class="pre">/</span></code>).</p>
<p>The function returns a binary string that is the contents of the specified
resource.</p>
<p>For packages located in the filesystem, which have already been imported,
this is the rough equivalent of:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="n">d</span> <span class="o">=</span> <span class="n">os</span><span class="o">.</span><span class="n">path</span><span class="o">.</span><span class="n">dirname</span><span class="p">(</span><span class="n">sys</span><span class="o">.</span><span class="n">modules</span><span class="p">[</span><span class="n">package</span><span class="p">]</span><span class="o">.</span><span class="vm">__file__</span><span class="p">)</span>
<span class="n">data</span> <span class="o">=</span> <span class="nb">open</span><span class="p">(</span><span class="n">os</span><span class="o">.</span><span class="n">path</span><span class="o">.</span><span class="n">join</span><span class="p">(</span><span class="n">d</span><span class="p">,</span> <span class="n">resource</span><span class="p">),</span> <span class="s1">&#39;rb&#39;</span><span class="p">)</span><span class="o">.</span><span class="n">read</span><span class="p">()</span>
</pre></div>
</div>
<p>If the package cannot be located or loaded, or it uses a <a class="reference internal" href="../glossary.html#term-loader"><span class="xref std std-term">loader</span></a>
which does not support <a class="reference internal" href="importlib.html#importlib.abc.ResourceLoader.get_data" title="importlib.abc.ResourceLoader.get_data"><code class="xref py py-meth docutils literal notranslate"><span class="pre">get_data</span></code></a>,
then <code class="docutils literal notranslate"><span class="pre">None</span></code> is returned.  In particular, the <a class="reference internal" href="../glossary.html#term-loader"><span class="xref std std-term">loader</span></a> for
<a class="reference internal" href="../glossary.html#term-namespace-package"><span class="xref std std-term">namespace packages</span></a> does not support
<a class="reference internal" href="importlib.html#importlib.abc.ResourceLoader.get_data" title="importlib.abc.ResourceLoader.get_data"><code class="xref py py-meth docutils literal notranslate"><span class="pre">get_data</span></code></a>.</p>
</dd></dl>

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